Locking away carbon dioxide by turning it into stable minerals underground is gaining attention as a reliable, long-term climate solution. It has already shown strong promise in certain rock types, especially basalt, where the process can happen relatively quickly. But what about other, less reactive rocks? Researchers Quanchao Zhou, Xuanming Shi, Leiyu Gu, Qinghai Zou, Yuxiao Xia, Jiangtao Pang, and Xiaying Li take a closer look at this question. In their study “Progressive Strength Degradation and Mineral Evolution in Tight Sedimentary Rock: Implications for Carbon Mineralization,” the authors explore how tight sedimentary rocks respond when exposed to supercritical CO₂ and water under conditions that mimic what happens deep underground.
The authors sought to better understand not only the chemistry but also how these rocks physically change over time. As carbon dioxide interacts with the rock, minerals can dissolve and new ones that form can gradually weaken the material. This interplay between chemical reactions and mechanical strength is important because it affects how safely CO₂ can be stored. Learn more about how carbon storage could expand beyond ideal rock types in the Journal of Energy Engineering at https://ascelibrary.org/doi/10.1061/JLEED9.EYENG-6536. The abstract is below.
Abstract
Carbon mineralization in geological formations is considered one of the most secure and permanent methods for long-term CO₂ storage. While extensive studies have focused on reactive basaltic systems, the behavior of tight sedimentary rocks under CO₂-rich conditions remains less understood, particularly regarding the coupling between mineral transformations and mechanical stability. This study investigates how mineral composition and micromechanical properties evolve in low-permeability sedimentary rock when exposed to CO₂-rich water under simulated reservoir conditions (60°C, 10 MPa) for up to 8 weeks. Using a combination of scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy, X-ray diffraction, and nanoindentation, we tracked progressive changes at both the microstructural and mineral scales. Results revealed early dissolution of calcite, minor changes in clay minerals, and stable silicate phases. SEM images showed increasing porosity and surface roughness, while nanoindentation measurements demonstrated a continuous decline in both hardness and elastic modulus over time. These findings suggest that CO₂–water–rock interactions in tight formations can lead to significant weakening of the rock framework, even as mineral trapping proceeds. Understanding this coupled chemical–mechanical evolution is essential for evaluating the long-term safety, sealing integrity, and performance of CO₂ geological storage in sedimentary environments.
Explore the potential for carbon sequestration in atypical sedimentary formations in the ASCE Library: https://ascelibrary.org/doi/10.1061/JLEED9.EYENG-6536.
